| We studied the effect of taurine, XOS and probiotic on performance, egg quality, biochemical parameters in serum and cholesterol and triglycerides in egg yolk, liver and follicle of laying hens in the paper, and detected the expression of rate-limiting enzyme-HMGR regulating synthesis of cholesterol and VLDLR acceptting cholesterol gene to explore the mechanism of deposition of cholesterol in laying hens providing scientific basis for production and research of low cholesterol eggs.In the first experiment we studied the effect of taurine, XOS and probiotic on performance and egg quality of laying hens. One thousand and five hundred healthy Roman laying hens of460days of age were randomly divided into eight treatments with setting four replicates of32chickens. Group method and additive of each group are as follows:the first group, the blank control (fed the basal diet); the second group,0.005%taurine; third group,0.015%XOS; the fourth group,2%probiotic; the fifth group,0.005%taurine and0.015%XOS; the sixth group,0.005%taurine and2%probiotic; the seventh group,0.015%XOS and2%probiotic; the eighth group,0.005%taurine,0.015%XOS and2%probiotic. The results showed that:(1) Compared with the control group, rate of egg production of the fourth group increased2.54%(P>0.05) in the whole period and feed to egg ratio of the second, third and fourth groups decreased by1.18%,0.79%,3.15%, but not significant (P>0.05).(2) Compared with the control group, egg-shape index of the second, fifth and seventh group decreased by5.93%,5.19%,7.41%and Haugh unit of the third and eighth groups increased by10.26%,12.96%significantly (P<0.05), and eggshell strength of the fifth and sixth group increased by12.77%,12.41%, but not significant (P>0.05) in21d; indicators of egg quality had certain change trend in42d, but not significant. The results showed that2%of the probiotic can improve production performance by increasing egg production and reducing the feed to egg ratio and0.015%XOS and three compound additives can significantly increase Haugh unit, improving protein quality.In the second experiment we studied the effect of taurine, XOS, and probiotic on biochemical index in serum and lipid metabolism of laying eggs on the basis of the first experiment. The experimental design was the same with design in the first experiment. The results showed that:(1) Compared with the control group, cholesterol in egg yolk of the fourth and sixth group decreased significantly by7.60%,8.20%(P<0.05) and triglycerides in egg yolk of the fourth and fifth decreased by21.94%,26.44%(P<0.05) in21d; cholesterol in egg yolk of the fifth, sixth and eighth group decreased by6.34%(P<0.05),9.72%(P<0.01),7.55%(P<0.05) and triglyceride in egg yolk of the fourth, fifth and sixth group was reduced by17.46%,17.35%,16.30%(P<0.05) in42d.(2) Compared with the control group, cholesterol, triglycerides and LDL cholesterol in serum of all groups showed a definite downward trend, but not significant in21d; HDL cholesterol of the eighth group was significantly reduced by46.88%(P<0.05) in42d, and biochemical parameters in other groups did not change significantly.(3) Compared with the control group, cholesterol in liver of the fourth and sixth group decreased by18.38%(P<0.05),12.13%(P>0.05) and triglyceride in liver of the third group significantly decreased by55.93%(P<0.05).(4) Compared with the control group, cholesterol and triglyceride in ovarian follicles of the fourth group were significantly reduced by23.46%,32.34%(P<0.05). The results showed that2%probiotic,0.005%taurine and0.015%XOS compound and0.005%taurine and2%probiotic compound can significantly reduce cholesterol and triglyceride in egg yolk, improving lipid metabolism of laying hen.In the third experiment we studied the effect of taurine, XOS and probiotic on regulation mechanism of cholesterol deposition based on the first and second experiment. The experimental design was the same with design in the first experiment. The results showed that:(1) Compared with the control group, the expression of HMGR gene in liver of the second, fifth, sixth, seventh, eighth group was reduced with the second, seventh group decreasing by45.31%significantly (P<0.05).(2) Compared with control group, the expression of VLDLR gene in ovarian follicles of all the groups was reduced with the second, sixth and seventh group decreasing by75.31%(P<0.01),53.09%,62.96%(P <0.05). The results showed that0.005%taurine,0.005%taurine and2%probiotic compound and0.015%XOS and2%probiotic compound control synthesis and deposition of cholesterol by regulating the expression of HMGR and VLDLR gene. |
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